JP2000231776A - Media server system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To write new data to a data storage area in real time by utilizing an idle time slot without disturbing data transmission. SOLUTION: A stream controller 4 of a media server 1 reads the data stored in a data storage area 5 and transfers the data to a network 2. A time slot is assigned for every player therefor. If a request is made to store new data in the area 5, the controller 4 assigns an idle time slot, that is not assigned to any of the players, for a data writing. If the time slot to be assigned to any one of the players for a data reading is deficit, the time slot already assigned to a player for a data writing is assigned to the player for the data reading.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a media server system which is widely used for distributing various data such as moving images and voices to a large number of media connected to a network.

[0002]

2. Description of the Related Art A media server stores media such as moving images, still images, voices, and texts in a database and distributes the data in real time via a network. The other party that distributes the data includes a player called a set pop, in addition to a workstation, a personal computer, and the like. This player is connected to a media server and receives a moving image or a still image, like a television receiver of a cable television system (CATV system).

[0003] A player has functions similar to a video deck, such as fast forward and reverse play of a moving picture, in addition to a normal moving picture reproducing function. That is, the video-on-demand system using the media server realizes a system that can reproduce a video from a desired position when the user wants to watch, replacing the conventional CATV system.

[0004]

However, the above-mentioned prior art has the following problems to be solved. Data to be distributed by the media server is stored in a database in a predetermined data storage area provided in the system. The media server reads out this data at a predetermined timing and sequentially distributes the data to many players. For data distribution, an application called a stream controller operates.

[0005] Moving pictures and sounds cannot be reproduced smoothly unless a certain transfer speed is maintained. The stream controller is required to have a detailed scheduling function for distributing data to a plurality of players while maintaining this transfer rate.

On the other hand, when the media server attempts to store new data to be distributed in the data storage area,
Stop the stream controller and run another application for data storage. However, in a video-on-demand system or the like, there is a strong demand to continue data distribution without a break for 24 hours. Therefore, if new data is to be written by interruption without stopping the stream controller, the scheduling function of the stream controller may be hindered.

[0007]

The present invention employs the following structure to solve the above problems. <Structure 1> A media server accesses a data storage area storing data to be distributed while allocating a time slot at a time interval equal to or less than a deadline for each player who has requested, reading the data and reading the plurality of data. A stream controller that distributes the data to the player, and an input data server that holds new data to be written to the data storage area, wherein the stream controller receives a request for writing new data from the input data server, An empty time slot not assigned to any player is detected, and the new data is assigned for writing to the data storage area and accessed, while a previous time is read for reading data to any player. Deadline counting from the assigned time slot The media server system if no empty time slots exist in the lower time already timeslots allocated for data writing, and allocates for data reading from the player.

<Structure 2> The media server accesses the data storage area storing the data to be distributed while allocating a time slot at a time interval equal to or shorter than the deadline for each requesting player, and reads the data. A stream controller for delivering to the plurality of players, and an input data server for holding new data to be written to the data storage area, wherein the stream controller keeps empty time slots in a predetermined cycle in advance. When there is a request to write new data from the input data server, the previously kept empty time slot is allocated for writing the new data to the data storage area, and access is performed. Media server system.

<Structure 3> In the media server system described in Structure 1, the stream controller keeps an empty time slot at a fixed period only in a time period limited in advance to write new data. Media server system characterized by assigning to a media server.

<Structure 4> In the media server system according to Structure 2, the stream controller allocates an empty time slot for writing new data only in a time period restricted in advance. Server system.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. In the present invention, while the stream controller controls data distribution to each player, the stream controller controls time slot allocation so that data can be written using an empty time slot without hindering the data distribution.

<Example 1> FIG. 1 is an explanatory diagram of a media server according to the present invention. Media server 1 shown in the figure
Configures a system to supply moving images, audio, and other various data to a large number of players 3 via the network 2. The media server 1 includes a stream controller 4, a data storage area 5, an input data server 6, a time slot management table 7, and the like.

The media server 1 comprises a workstation or the like which holds media such as moving images and still images and distributes the data to a plurality of players via a network. The player is a terminal device having a function of reproducing a moving image, a still image, sound, or the like, such as a video deck. In the data storage area 5 of the media server 1,
The media server stores data to be distributed. This data is a database of media such as moving images, still images, audio, and text.

The stream controller 4 is an application having a function of accessing the data storage area 5 to read data and delivering the data to the player 3 who has made the request. The stream controller 4 receives data distribution requests from a plurality of players 3 at the same time. The stream controller 4 has a scheduling function for distributing data while maintaining a constant transfer rate for each player. For this purpose, alternate data reading and distribution are performed while allocating time slots T1, T2,... Having a fixed time width to each player.

The assignment of time slots to one player is performed at intervals equal to or less than the deadline. The deadline is the maximum data read interval allowed to maintain the transfer speed. If it is equal to or less than the deadline, a time slot can be allocated to the same player at an arbitrary time interval.

For example, the time slot T1 shown in FIG.
T9 is the time for one block allocated for transferring data, and the time slot boundaries are shown. A time slot indicated by an asterisk in the figure is allocated, for example, for reading data to the player P1. If it is assumed that only the player P1 is currently requesting data, a time slot for writing data is freely provided in a time slot other than the portion indicated by *. The time slots marked with # in the figure are portions assigned as time slots for writing data by the input data server 6.

According to the present invention, an input data server 6 for holding new data to be written in the data storage area of the media server is prepared. This input data server 6
It may be constituted by a predetermined storage device provided inside the media server 1 and a transfer control program, or by a workstation or the like which is located away from the media server 1 and connected to the media server by a communication line. You may comprise. The input data server 6 requests the stream controller 4 to write new data to the data storage area 5 without interrupting the operation of the stream controller 4.

The stream controller 4 has the following functions in order to respond to this request. When there is a request for writing new data by the input data server 6, an empty time slot not allocated to any player is detected and allocated for writing new data. The input data server 6 prepares a time slot management table 7 indicating which time slot has been assigned to all the players 3 that have requested data distribution. By searching this table, an empty time slot can be easily detected.

In writing new data, there is no deadline in the transfer speed. This is because there is no limit on the storage time. Further, as long as there are free time slots, all free time slots can be allocated to writing new data. When a new player makes a data distribution request, the time slot already allocated for data writing is released, and the time slot is allocated to data reading to that player. This is for giving priority to data reading and permitting data writing within a range that does not hinder the data reading operation.

In some cases, an empty time slot cannot be detected within a time equal to or less than the deadline, counting from the time slot previously allocated for reading data to any player. In this case, a time slot already assigned for writing data is assigned for reading data to the player. Thus, new data can be written to the data storage area without hindering access to the data storage area in response to a data distribution request by a plurality of players.

FIG. 2 is an explanatory diagram of a specific time slot assignment operation. As shown in (a) of the figure, when time is taken on the horizontal axis, for example, a time slot for reading data for each player is allocated every 3 milliseconds. Displaying T1, T2, T3,... In each time slot results in the state shown in FIG. The time slots T1, T2, and T3 are sequentially assigned to the player P, respectively.
1, P2, and P3.

Here, assuming that, for example, an interval of 10 time slots is a deadline, a time slot for data reading is allocated to the same player every 8 time slots for safety. This time interval is shown as W in the figure. In this case, the time slots T4 to T8 shown in the figure become empty time slots. As described above, it is rare that all the players are playing back, and there are usually many empty time slots.

Further, even when the player is connected, the moving image is not always reproduced continuously. For example, some are in menu selection, paused, or idle. A time slot for writing data is allocated by removing such a gap. Here, time slots T5, T6 or time slots T12, T1
4 is assigned a time slot for writing data. All empty time slots may be allocated for writing.

Here, if the player P4 requests a new connection and the data needs to be read, the time slot allocated for data writing is allocated for data reading.

FIG. 3 is an explanatory diagram of a compulsory assignment method according to the first embodiment. Here, it is assumed that, for example, the player P5 is assigned the time slot T5 to read data, and then assigns the next time slot. Here, it is assumed that all empty time slots have been allocated for data reading. In this case, it is necessary to assign the data readout to the player P5 at least until the time slot T15.
Beyond this, you will cross the deadline.

Therefore, for example, the time slot T13 allocated for writing data is forcibly allocated for reading data to the player P5. FIG. 4 shows a specific procedure for performing such processing.

FIG. 4 is an operation flowchart of the first embodiment. In step S1 of the figure, the stream controller 4 receives a command from the player 3 or the input data server 6. In step S2, it is determined whether the request is a read request or a write request. If it is determined that the input data server 6 has made a data write request, the time slot management table 7 shown in FIG. 1 is referenced to search for an empty time slot as shown in FIG. 2B. Then, the data transferred from the input data server 6 is inserted into a vacant place, and data writing control to the data storage area 5 is performed (step S3).

On the other hand, in step S2, the player 3
When it is determined that a data read request has been issued from the player, the process proceeds to step S4, and the number of time slots between the previous data read to the player and the current data read is counted. This is the time slot management table 7
May be referred to. Then, it is determined whether there is a vacant time slot before the deadline.

If there is a vacant time slot,
Proceeding to step S5, the time slot is assigned to data reading. If not, the process proceeds to step S6, and it is determined whether there is a write command before the deadline. As shown in FIG. 3, when a write command is present in the time slots T13, T14, T15 up to the deadline, the process proceeds to step S7, and a time slot for reading is assigned to that location.

On the other hand, if there is no write command, the process proceeds to step S3, and the read is assigned at the earliest time after the deadline. That is, in this case, even if data loss occurs, it is unavoidable.

<Effects of Specific Example 1> As described above, according to this specific example, the stream controller 4 uses the empty time slot to insert data without interrupting the operation of distributing data to the player 3. Since data is stored by the data server 6, necessary data can be quickly stored in the data storage area 5 and used for distribution.

<Specific Example 2> In the specific example described above, the stream controller 4 sets the data storage area 5 in which the data to be distributed by the media server 1 is stored for each of the requested players in a time equal to or less than the deadline. It accesses while allocating time slots at intervals, reads out data, and distributes it to a plurality of players.

However, it is good if there are enough free time slots, but if there are not enough free time slots, when a large amount of data is to be stored in the data storage area 5, by what time will the storage operation end? There is a problem of not knowing. Further, in the case where the input data server 6 is located far away from the media server 1 and stores data through a communication line or the like, if the communication line is kept connected until all the data is stored, communication costs will increase. Can be expensive.

Therefore, a buffer memory for transferring and storing data to be stored in the media server 1 is prepared. This requires an extra data storage area on the media server 1 side. Therefore, in this example, a data writing speed equal to or higher than a certain value is secured. For that purpose, the stream controller 4 keeps empty time slots in a fixed cycle in advance. Keeping a time slot means prohibiting allocating a kept empty time slot to data reading. The remaining time slots are allocated for reading data.

When a request for writing new data is made by the input data server, an access is performed by allocating a previously kept empty time slot for writing new data into the data storage area.

FIG. 5 is an explanatory diagram of the assignment method according to the second embodiment. As shown in the figure, for example, in this example, time slots are kept at a constant cycle for writing data. The kept time slots are, for example, T7, T17, T27, T
37. It is sufficient to secure at least such a data writing speed, and when there is a free time slot more than that, the free time slot may be allocated to data writing.

Accordingly, it is possible to control such that only the time slots kept in this way are dedicated to data writing, and the other time slots are given priority to data reading, and if the time slots are free, they are assigned to data writing.

<Effect of Specific Example 2> Since a dedicated time slot is reserved for data writing, the minimum data writing speed can be secured, and practical data writing processing can be performed in real time. become.

<Specific Example 3> As described above, if the time slots are always kept empty, the maximum number of players to which data can be distributed is limited. On the other hand, for example, in a video-on-demand system, the total number of players who request data decreases at midnight or early morning. In such a time zone alone, there is no problem even if the maximum number of players that can be distributed is limited. Therefore, empty time slots are kept at a fixed period only in a time zone limited in advance, and are allocated for writing new data.

More specifically, a time slot dedicated to data writing is kept in the period from 1:00 a.m. to 5:00 a.m. Then, at other times, the control of the specific example 1 is performed.

FIG. 6 shows an operation flowchart of the third embodiment. Step S1, Step S2, Step S in FIG.
The processing from Step 8 to Step S11 is the same as that in the specific example 1 described with reference to FIG. When it is determined in step S2 that there is a write request from the input data server 6, the processing differs. First, in step S3, it is determined whether the time is within the time limit. Whether the time is within the time limit is a determination as to whether or not the time corresponds to the midnight time just described. The determination of the time is performed using a clock or the like (not shown) provided in the system.

That is, if it is not midnight, for example, step S6
And if a time slot is free, assign a write request to that location. Therefore, if it is not empty, the write request is ignored. On the other hand, if it is determined that it is midnight, the process proceeds from step S3 to step S4 to determine whether the number of terminals can be limited.

For example, in a video-on-demand system, the number of players requesting data generally decreases during the late night or early morning hours. However, when there is a special event or on the eve of a holiday, the stream controller may continue to operate with the maximum number of players that can be distributed. In such cases, keeping the time slots for writing is commercially inefficient.

Therefore, it is determined in step S4 in FIG. 6 whether or not such a case is applicable. If the number of connected terminals can be limited, the process proceeds to step S4, where the number of connected terminals is limited.
Keep available time slots. And step S
Then, the process proceeds to 6, and data write processing is assigned to an empty time slot. Although data writing is performed while limiting the number of terminals in this way, there is no need to limit the number of terminals when the writing is completed. In step S7, when the writing is completed, a process for removing the terminal restriction is performed.

<Effects of Specific Example 3> As described above, if the number of terminals that can be connected while keeping an empty time slot only during a certain period of time is limited, a sufficient writing time can be secured. A large amount of data can be input in real time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a media server of the present invention.

FIG. 2 is an explanatory diagram of a time slot assignment operation.

FIG. 3 is an explanatory diagram of a compulsory assignment method according to a specific example 1.

FIG. 4 is an operation flowchart of a specific example 1.

FIG. 5 is an explanatory diagram of a compulsory assignment method according to a specific example 2.

FIG. 6 is an operation flowchart of a specific example 3.

[Explanation of symbols]

 1 Media Server 2 Network 3 Player 4 Stream Controller 5 Data Storage Area 6 Input Data Server 7 Time Slot Management Table

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C053 FA14 FA20 FA23 FA28 GB06 GB11 GB40 HA29 JA03 JA21 KA05 KA21 KA24 LA06 LA14 5C064 BA01 BB10 BC10 BC18 BD02 BD07 5D110 AA13 AA17 AA19 AA27 AA29 BB20 DA14 DB08 DE01

Claims (4)

[Claims] 1. A media server accesses a data storage area in which data to be distributed is stored while allocating a time slot at a time interval equal to or less than a deadline for each requested player, and reads out the data. A stream controller that distributes the data to a plurality of players; and an input data server that holds new data to be written to the data storage area, wherein the stream controller receives a request for writing new data from the input data server. While detecting an empty time slot not assigned to any player and allocating and accessing the new data for writing to the data storage area, and for reading data to any player. Dead from the last assigned time slot The media server system when no idle time slots are present within the following times in already timeslots allocated for data writing, and allocates for data reading from the player. 2. A media server accesses a data storage area in which data to be delivered is stored while allocating a time slot at a time interval equal to or less than a deadline for each requesting player, and reads out the data. A stream controller for delivering to a plurality of players; and an input data server for holding new data to be written to the data storage area. The stream controller keeps empty time slots at a predetermined cycle in advance, When there is a request for writing new data from the input data server, the media server allocates the previously kept free time slot for writing the new data to the data storage area and performs access. system. 3. The media server system according to claim 1, wherein the stream controller keeps an empty time slot at a predetermined cycle only in a time period limited in advance to write new data. A media server system characterized by assigning. 4. The media server system according to claim 2, wherein the stream controller allocates an empty time slot for writing new data only in a time zone that has been restricted in advance. system.